Electromagnetic horn



Patented Aug. 19, i947 UNITED STATES PATENT OFFICE ELECTRMAGNETIO HORNApplication July 24, 1937, Serial No. 155,489

d Claims.

The present invention relates to electric communication. Y

The invention will beodescribed more `fully in connection with theaccompanying drawing, the single gure of which is a diagrammatic View ofcircuits and apparatus embodying Vthe present invention, showing,` .inlongitudinal section, an electromagnetic horn Aconnected to a coaxialpipe.

An electromagnetic'horn 83, or" circular or annular dared-outconformation,` is shown at the free open end of an elongated tubularorpipe body portion or section Btg that may extend over any desireddistance from the small end or throat of the horn. Thehorn may beconstituted of metal, such as copper or aluminum, or it may beconstituted of other material i1" its inner wall is otherwise rendered aconductor of the waves. The electromagnetic horn is provided with a,guiding surface or guiding walls that connect the small endor the throatand the large end lor the mouth of the horn.V The horn thus operates toguide waves traveling within it and tangentially along its surface inthe longitudinal direction,` smooth- 1y and Without interruption. Inreception, electromagnetic Waves received from space at the mouth of thehorn are guided to the throat end of the horn. Intransmission,Velectromagnetic waves generated at the small end of the horn aredirected forward out into space.

The pipe `,.leconstitutes the outer tubular conductor of a coaxial-cableor `co'aXial-lineor coaxial-feed transmitting system 912, 94, theextended inner or central conductor. $2` of which maybe supportedsubstantiallycentrally i nvand spaced from the `walls o f, the tube im,largely along the axis of the pipe 9d andthe horn 88, by insulatingmembers (not shownh The central conductor 92 extendsinside the tubularmember 94, 83, and into the throat ofthe hln t3, Where it terminates, toprovide therein a free terminal beyond which the conductor 92 doesnotextend. The portion of the conductor S2 in the neighborhood of thefree terminal is shown vdeparting somewhat iromthe` Said axis.` Thisfree terminal is continuously joined to one end of an Aexciting orabsorbing loop antenna rod El, the other end I of which is shownconnected to the horn et.

The rod 8l isillustrlated as disposed in a plane through, andsubstantially at right angles to, the said axis. Itis shown positionedapproximately centrally directly in the throat of the horn, outwardly ofany portion of thejhorn, such as the pipe 94, that may be ofsubstantially uniform cross section. f y f output circuit.

,2 Y The rod 8l thus constitutes a connecting conductor, disposed insidethe tubular membe1` 88;.941,

for connecting the said free terminal of the conductor 92 to the tubularmember 94, thus to provide a continuous conducting path'fo-r carryingcurrent between the tubular member 94 `and the conductor 92 of thecoaxial line. This construction enables the rod Vlil to excite Vorintercept -electromagnetic waves.

To this end, the rod 8l may be connected to terminal apparatus, as bymeans of two-wire connecting leads lil and l2. One oi the leads, vasthewire It, may be connected to the outer tubular conductor et, and theother lead, as the Wire I2, to the central conductor 92 of the`coaxial-'feed line. The terminal apparatus may be connected to sendingor receiving apparatus, at a sending or receiving station. For sending,the leads l0 land l2 may be connected to means for energizing theantenna 3l'. For receiving, they may be connected to means forAevidencing the received waves absorbed by the antenna 8l.

The horn is shown Vconnected to a transmitting system comprising aradio-frequency oscillator 2, provided with a modulator 3, which may bemodulated in any desired way, as by means of a microphone 4. Themodulated output may be fed to a radio-frequency amplifier E that may becoupled to a circuit 8 having the leads l0 and I2 in its The describedmeans of connecting the horn 83 to the coaxial-line "92194 provides anexciting rod lll substantially tranverse to the axis of the pipe and thehorn for beam transmission. The modulated ultra-high-frequency energymay be taken by the conductors lil and l2 from the sending apparatus anddelivered to the antenna tl in the small end of the horn. Current wavesin the antenna 81 become impressed from the central conductor 92 uponthe rod 8l. The antenna Sl will excite modulated ultra-high-frequencyelectromagnetic` waves of horn type, or horn waves, near the small endof the horn. The Waves will be transversely polarized, that is, theelectric intensity will be entirely in surfaces normal to the directionof propagation. These transversely polarized waves will be propagatedthrough the interior of the horn toward the large end or the mouththereof, and finally beyond the mouth of the horn, into free space, `asordinary radio waves. A beam will be radiated from lthe horn mouth ofcharacter appropriate to the horn itself; rather than to the antenna 8land the other apparatus.

Similar but reverse operation will take place for reception of thewaves, the large end or the mouth of the horn being electromagneticallyopen to space to permit the horn to receive electromagnetic waves fromspace. Modulated ultrahigh-irequency electromagnetic waves, received atthe mouth of the horn, will be communicated to the antenna 8l, by whichthey will be absorbed, after which the energy will be conducted down thehorn and the pipe to be delivered to the receiving apparatus (notshown), Where the signal comprising the intelligence will be recoveredby demodulation.V

A coaxial-type wave transmitted along the tubular member 94 and theconductor 92 disposed therein, therefore, will be converted into atransverse-electric-type Wave in the tubular member 94 beyond theconnecting conductor 81; or vice versa, a transverse-electric-type wavein the tubular member beyond the connecting conductor 81 may beconverted into a coaxial-type Wave transmitted along the tubular memberand the conductor 92 disposed therein. 'I'he waves will not be morefully described herein because they will be understood without furtherdescription by reference to a paper by L. J. Chu and W. L. Barrow,entitled, Electromagnetic waves in hollow metal tubes of rectangularcross section, proceedings of the Institute of Radio Engineers, vol. 26,No. 12, December, 1938, commencing at page 1520, and also to a paper byBarrow, entitled, Electromagnetic-horn radiators, Union RadioScientifique Internationale, No. 79, p. 277, containing a revision of apaper presented at the Joint Meeting of the said Union and the Instituteof Radio Engineers, at Washington, D. C., April 30, 1938. See also apaper by W. L. Barrow and L.. J. Chu, entitled, Theory of theelectromagnetic horn, Proceedings of the Institute of Radio Engineers,vol. 27, No. 1, January, 1939, commencing at page 51, and also a paperby W. L. Barrow and F. D. Lewis, entitled, The sectoral electromagnetichorn, Proceedings of the Institute of Radio Engineers, vol. 27, No. 1,January, 1939, commencing at page 41.

The invention is not limited to the exact embodiment thereof that isillustrated and described herein. Modiiications may be made by personsskilled in the art without departing from the spirit and'scope of theinvention, as defined in the appended claims.

What is claimed is:

1. An electric system having, in combination, anelectromagnetic-wave-guide horn having a small end and a large end, thelarge end being electromagnetically open to space to permit the horn toreceive electromagnetic waves from space or to radiate electromagneticwaves out into space at the large end, absorbing or exciting antennameans disposed in the horn at the small end, the horn having guidingwalls between the large end and the small end for guiding the wavesreceived from space at the large end to the antenna means at the smallend in order that the received waves may be absorbed by the antennameans or for guiding to the large end for radiation out into space thewaves excited by the antenna means at the small end, coaxial-line meansfor connecting the antenna means with means for evidencing the receivedwaves absorbed bv thel antenna means or with means for energizing theantenna means to excite at the small end the Waves to be radiated outinto space, the coaxial-line means having a substantially centrallydisposed conductor connected to the antenna means and an outer tubularconductor connected to the horn, and means for connecting the antennameans to the outer tubular conductor.

2. An electric system having, in combination, anelectromagnetic-wave-guide horn having a small end and a large end, thelarge end being electromagnetically open to space to permit the horn toreceive electromagnetic Waves from space or to radiate electromagneticwaves out into space at the large end, absorbing or exciting antennaloop means disposed in the horn at the small end, the horn havingguiding walls between the large end and the small end for guiding thewaves received from space at the large end to the antenna means at thesmall end in order that the received waves may be absorbed by theantenna means or for guiding to the large end for radiation out intospace the waves excited by the antenna means at the small end,coaxial-line means for connecting the antenna means with means forevidencing the received waves absorbed by the antenna means or withmeans for energizing the antenna means to excite at the small end theWaves to be radiated out into space, the coaxialline means having asubstantially centrally disposed conductor connected to one portion ofthe loop means and an outer tubular conductor connected to the horn, andmeans for connecting another portion of the loop means to the outertubular conductor.

3. An electric system having, in combination, an absorber or radiatorfor receiving electromagnetic waves from space or radiatingelectromagnetic waves out into space, absorbing or exciting antennameans disposed in the absorber or radiator, coaxial-line means forconnecting the antenna means with means for evidencing the receivedwaves absorbed by the antenna means or with means for energizing theantenna means to excite the waves to be radiated out into space, thecoaxial-line meansA having a substantially centrally disposed conductorconnected to the antenna means and an outer tubular conductor connectedto the absorber or radiator, and means for connecting the antenna meansto the outer tubular conductor.

4. A conductor of electromagnetic waves having, in combination, acoaxial line comprising a conducting tubular member and a conductordisposed substantially centrally of the tubular member and terminatinginside the tubular member to provide in the tubular member a freeterminal beyond which the conductor does not extend, and meanscomprising a connecting conductor in the tubular member connecting thefree terminal to the tubular member and carrying current between thetubular member and the conductor disposed therein to convert acoaxial-type wave transmitted along the tubular member and theconductorl disposed therein into a transverseelectric-type wave in thetubular member beyond the connecting conductor, or to convert atransverse-electric-type wave in the tubular member beyond theconnecting conductor into a coaxial type wave transmitted along thetubular member and the conductor disposed therein.

WILMER L. BARROW.

REFERENCES CITED The following references are of record in the file ofthis patent:

(References on following page) 5 UNITED STATES PATENTS Number l NumberName Date 2,052,339 Dallenbach Aug. 25, 1936 2206683 2,106,768Southworth Feb. 1, 1938 2,044,413 Weyrich June 16, 1936 5 2,129,712Southworth Sept. 13, 1938 Number 2,129,711 Southworth Sept. 13, 1938 466063 2,054,896 Dallenbach Sept. 22, 1936 798579 2,943,347 Clavier June 9,1936 430646 2,161,292 Hahnemann June 6, 1939 10 2,039,812 Leib May 5,1936 1,696,304 Hutchison Dec., 25, 1928 741,622 Brown Oct. 20, 1903986,806 DAntono Feb. 14, 1911 1,828,705 Konter oct. 20, 1931 15 284 309Name Date Darbord Aug. 22, 1933 Southworth July 9, 1940 Wolff July 2,1940 FOREIGN PATENTS Country Date Great Britain May 21, 1937 France Mar.10, 1936 Great Britain June 21, 1935 OTHER REFERENCES Annalen der PhysikV. 21, Oct. 1934, pp. 113-138 (Copy in Patent Ofce Library.)

Bell System Tech. Journal, Apr. 1936, V. 15, pp.

(Copy in DV. 16.)

